Sorry in advance for a potentially dumb newbie question, but here goes.

I am learning web app programming and I would like to have an input textbox on my webpage where the user enters some text. Then I capture that text and pass to a perl script which generates some output. I then take this text output and pass it back to the webpage.

Can someone point me in the right direction on how to do this.

Can be a really simple example, where the user inputs some text. I take the text and pass to a perl script which turns everything to uppercase - uc() - and then passes back to the webpage.

The page needs to contain a form. The action attribute of the form needs to point to a URL that your webserver will process with the Perl program. The simplist way to achieve this is using CGI, a more modern approach uses PSGI. Most Perl form processing libraries use a similar interface to CGI.pm's